2004 kia optima overheating when in town driving. have to run heater for temperature to go back down. Shop told me the only thing wron is the drive belt and they couldn's get it to overheat. Eversince ive had it bback it has overheated. Car seems to be okay on freeway, then with stop and go it overheats.

I had this same problem with the same car. I changed the thermostat, temp sensor, water pump and timing belt and it still overheats with the AC on primarily.

Classic signs of a bad water pump. When on the freeway, the circulation of coolant through the system is increased due to the speed but once you slow down, it will tend to overheat. Please post back with any other questions or just to rate the solution. Thanks very much!
Greg

Lack of air flow through radiator. Check that the fan(s) - relay controlled electric or belt driven fans are working at idle. Check that there is no debris blocking air flow and the radiator cooling fins are not blocked.
Some bug covers or hood bras greatly decrease air flow.